Recycled cardboard bike on the cheap

Bicycle design has taken a turn into wild, wacky and innovative territory as designers create bamboo bikes, cardboard bikes and even bikes that fly.

Inventor Izhar Gafni built this bicycle out of $9 worth of cardboard in 2012. The recycled machine made quite a splash as an idea that could potentially work for people in developing countries. An attempt at crowdfunding the idea in 2013 went nowhere near its goal, but the concept is still a fascinating one.

Zombie-destroying bike

When gas shortages kick in after the zombie apocalypse, you'll be glad you have a zombie-proof bike. This special ride was designed by UK insurance company ETA. It features a hatchet, electric chainsaw and a flamethrower. The best idea of all is the splatter shield, included to keep all those icky zombie guts off you as you pedal your way to safety.

This bike flies on propeller power

Who says bicycles have to be stuck on the ground? Several Czech companies got together and built a flying electric bike that looks like a really big RC copter. The bike went through a successful test flight with a dummy onboard. It levitates thanks to six battery-powered propellers. It might not be practical on the street, but it sure is cool.

Electric bike folds up small

Some electric bikes are big and bulky. That's not a problem for the Gi Bike, an electric ride that weighs just over 37 pounds (17 kilograms). It's not just the weight that makes it packable, it also folds up into a compact form for storage or hauling around. The battery is good for revving you around for up 40 miles (64 kilometers).

The Gi has other high-tech features, like the ability to charge up your smartphone and built-in safety lights. It's also controlled by a mobile app. The fancy bicycle didn't reach its Kickstarter goal, but the designers are talking with manufacturers about moving ahead anyway.

Cool bike rides on ice

Everybody wants a cool ride. Mad scientist Colin Furze took on the challenge of modifying an existing BMX bike and swapping out the regular tires with ones made of ice. The resulting Ice bike actually works, it just doesn't work very well on hills where the tires get slippery. Still, it sounds like quite the maker project for wintery weather.

High-concept bike for kids

Adults aren't the only ones who should have fun with unusual bikes. The Miilo bike is a clever contraption that switches from a foot-powered push-bike that's low to the ground to a full-on pedal-powered wonder. It's the same bike, but swappable components allow it to grow with its kid rider. It's a clever way to have a bike that lasts, even as your child gets bigger.

A bike that can't be swiped

Bikes are constantly under threat of being stolen. A lot of effort has gone into developing locks that make it hard to make off with a bike, but it's only more recently that an entire bicycle has been dedicated to the cause. Three engineering students from Chile developed a bike design called the Yerka Project. The frame opens up to act like a giant lock. Stealing it would require breaking the frame. That should be enough to deter almost any robber.

Ultimate urban bike goes into production

The Oregon Manifest Bike Design Project put out a call for creators to build the ultimate urban utility bike. Seattle design firm Teague teamed up with custom bike company Sizemore to create the Denny, the bike that ultimately won the competition.

Denny has a handlebar that doubles as a lock, plus turn signals, automatic lights, integrated storage and an onboard computer that shifts gears according to the terrain. The bike will be built by Fuji and offered at retail. No word on pricing yet, but it's bound to be a coveted item for the urban road warrior.

Light up your bike life

The Orfos Flares Kickstarter project isn't a full-on bike, but rather a bike accessory that aims to make bicyclists extremely visible at night. The lights are made of LED bulbs embedded in clear silicone, creating a taillight as bright as a car's. The headlight is equivalent to a car's daytime running lights.

The result of the Orfos system is that a bike is engulfed in a pool of light. It's all about making yourself more noticeable. The concept has proven popular by handily exceeding its Kickstarter funding goal. Backers should be receiving their lights by the end of the year.

A bamboo bike you build yourself

Kickstarter has been a sort of proving ground for all sorts of bike and bike accessory projects. It's currently home to an unusual bike that combines renewable resources with a DIY philosophy. The Bamboobee Build It Yourself (BIY) is a kit that includes bamboo, hemp fiber, a frame jig and a few other components needed to make your own bamboo bike frame.

You get to choose and provide your own finishing components (like wheels) to customize the bike to your liking. The BIY kit has topped its funding goal by nearly threefold.